Shirley Polykoff, 90, Ad Writer Whose Query Colored A Nation

Shirley Polykoff, the pioneering advertising woman who came up with a single double-entendre that changed the face, or rather turned the heads, of American society, died on Thursday at her home on Park Avenue. She was 90 and the author of the ''Does she . . . or doesn't she?'' slogan, which unleashed American women to choose the color of their hair.

In an era when hair color is no longer a fiat of nature but a routine fashion choice, it is easy to forget that as recently as the mid-1950's hair coloring was such an exotic exception to a cultural norm that only 7 percent of American women dared dye their hair, mainly actresses, models and other fast women.

Then in 1956 Miss Polykoff invented the ''Does she . . . or doesn't she?'' campaign for a tiny Bristol-Myers division known as Clairol. Almost overnight, the slogan became a national catch phrase, and dyed hair (although never thereafter, she made sure, known that way) went from declasse to de rigueur.

Attracted by the slogan and its reassuring tag line, ''Hair color so natural only her hairdresser knows for sure,'' within a decade nearly half of all American women were regularly coloring their hair, and sales of dyes, tints and rinses had soared from $25 million to $200 million a year, with Clairol accounting for more than half the total (as it does today with industry sales of more than $1 billion).

Once the lone female copywriter at the giant Foote, Cone & Belding advertising agency, Miss Polykoff became the agency's lone female executive vice president, the toast of Madison Avenue and the 1967 Advertising Woman of the Year.

For the Brooklyn-born middle daughter of Russian Jewish immigrants, especially one whose mother wanted her to be a boy, the triumph was hardly a fluke. From the time she was 11 and made ''$3 and change'' for 12 hours' work selling coats in a Brooklyn department store, Miss Polykoff had relished proving herself in the traditional masculine role of breadwinner.

By the time she arrived at Foote, Cone & Belding in time to take over the new Clairol account in 1955, Miss Polykoff, who had written her first advertising copy as a teen-age secretary at Harper's Bazaar, had long since established herself as a star in retail advertising, first for a series of department and variety stores, including Bamberger's and Kresge in Newark, then for New York agencies with retail accounts.

As one of the few women in a male-dominated industry selling almost exclusively to women, the traditional household purchasing agents, Miss Polykoff had an advantage over her sometimes obtuse colleagues, particularly those who told her the proposed ''Does she . . . or doesn't she?'' campaign was too suggestive.

In her 1975 book, ''Does She . . . or Doesn't She? And How She Did It,'' Miss Polykoff recalled that when similarly obtuse executives at Life magazine turned down a 10-page Clairol layout because of the double-entendre, she challenged them to poll the women in the magazine office.

When the dirty-minded executives could not find a single woman who thought the line had any smutty connotation, Miss Polykoff was not surprised. She had realized all along that well brought-up women of the 1950's, the Clairol target audience, would never admit, as she put it, ''that a nice girl ever got an off-color meaning about anything.'' The ad ran, and, as she recalled, ''everybody got rich.''

To some latter-day feminists, Miss Polykoff was somewhat perplexing, on the one hand an obvious pioneering role model for professional women, on the other a woman whose success, which included such campaigns as ''Is It True Blondes Have More Fun?'' and ''If I've Only One Life to Live, Let Me Live It as a Blonde,'' depended on catering to women's vanity as sex objects.

Miss Polykoff, who frankly used her femininity to charm men and who chided modern businesswomen who try to ape men, did not apologize. For all her ambition and outsized success as a woman, Miss Polykoff was cut from a pre-feminist mold, never forgetting, as she often put it, that she was ''a girl first and an advertising woman second.''

Growing up as the awkward middle daughter between two raven-haired beauties, Miss Polykoff, who saw her blond hair as her only physical distinction (at least until she began to develop what she called her ''sexy curves''), was so distraught when her hair began to darken as a teen-ager that she began having a local hairdresser lighten it, just to make the back match the front. That fiction sufficed until her future mother-in-law secretly asked her son the Yiddish foreshadowing of ''Does she . . . or doesn't she?''

Miss Polykoff also unabashedly put husband and family above her career, going so far as to hold her Foote, Cone salary to $25,000 so as not to earn more than her lawyer husband, George P. Halperin. After he died in 1961, the agency doubled her salary twice in less than a decade, and when she retired in 1973 to open an agency under her own name she had been Foote, Cone's highest paid salaried employee for many years.

She is survived by two daughters, Laurie Zucker of Athens, Ohio, and Alix Nelson Frick of Manhattan, the president of Franklin Spier Advertising; a sister, Lillian Ovberg of Glen Cove, N.Y., and three grandchildren.

Correction: June 15, 1998, Monday An obituary last Monday about Shirley Polykoff, the advertising woman who devised the slogan ''Does she . . . or doesn't she?'' in 1956 to advertise hair coloring products, referred incorrectly to the ownership of the advertiser, Clairol. The company was independent at the time. It was acquired in 1959 by the Bristol-Myers Company, now Bristol-Myers Squibb.